an empirical study of realvideo performance across the internet
DESCRIPTION
An Empirical Study of RealVideo Performance Across the Internet. Yubing Wang, Mark Claypool and Zheng Zuo http://perform.wpi.edu/real-tracer. Introduction. Streaming Audio and Video is growing Traditional Internet studies, but ….video is different Bandwidth and response time not enough - PowerPoint PPT PresentationTRANSCRIPT
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An Empirical Study of RealVideo Performance Across the Internet
Yubing Wang, Mark Claypool and Zheng Zuo
http://perform.wpi.edu/real-tracer
![Page 2: An Empirical Study of RealVideo Performance Across the Internet](https://reader035.vdocuments.mx/reader035/viewer/2022070404/56813afd550346895da391f6/html5/thumbnails/2.jpg)
November 2001 SIGCOMM Internet Measurement Workshop
Introduction
• Streaming Audio and Video is growing
• Traditional Internet studies, but ….video is different– Bandwidth and response time not enough
• Care about smooth rate
– Packet loss rate alone is not enough• Often use repair techniques
• RealVideo is big [Jup01]
– RealPlayer, MediaPlayer, QuickTime
Measure RealVideo on Internet
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November 2001 SIGCOMM Internet Measurement Workshop
Outline
• Introduction
• RealVideo
• Methodology
• Results
• Analysis
• Conclusions
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November 2001 SIGCOMM Internet Measurement Workshop
RealVideo Network Characteristics
• Buffering
• SureStream
• Scalable Video Technology
• Repair
Server
RTSP
Data: TCP or UDP
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November 2001 SIGCOMM Internet Measurement Workshop
Outline
• Introduction
• RealVideo
• Methodology
• Results
• Analysis
• Conclusions
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November 2001 SIGCOMM Internet Measurement Workshop
Methodology
• Build customized RealVideo player (RealTracer)– Uses RealPlayer core
– Software Development Kit (SDK)
– Records performance stats: frame rate, jitter ….
• Select diverse set of RealVideo servers and videos
• Solicit volunteers to run RealTracer– Many users to Many servers
– Friends, colleagues outside of Mass., U.S.
– rec.video newsgroup and end2end mailing list
– 2 weeks in June 2001
• Analyze results
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November 2001 SIGCOMM Internet Measurement Workshop
Outline
• Introduction
• RealVideo
• Methodology
• Results
• Analysis
• Conclusions
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November 2001 SIGCOMM Internet Measurement Workshop
TCP UDP
Results
• 11 servers in 8 countries
• 63 users in 12 countries
• 2855 video clips played
• 388 video clips watched and rated
• 10% chance clip unavailable
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November 2001 SIGCOMM Internet Measurement Workshop
Geographic Location of Servers and Clients
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November 2001 SIGCOMM Internet Measurement Workshop
Clips Played per User
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 20 40 60 80 100
Clips Played per User
Cu
mu
lati
ve
De
nsi
ty
.
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November 2001 SIGCOMM Internet Measurement Workshop
Outline
• Introduction
• RealVideo
• Methodology
• Results
• Analysis– Frame Rate – Jitter– Perceived Quality
• Conclusions
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November 2001 SIGCOMM Internet Measurement Workshop
Frame Rate
• Basic video performance unit– frames per second (fps)
• Guidelines [Rea00a]:
– 24-30 fps: full-motion video
– 15 fps: full-motion video approximation
– 7 fps: choppy
– 3 fps: very choppy
– Less than 3 fps: slide show
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November 2001 SIGCOMM Internet Measurement Workshop
Overall Frame Rate
00.1
0.20.30.40.5
0.60.70.8
0.91
0 5 10 15 20 25 30
Average Frame Rate (fps)
Cu
mu
lati
ve D
en
sit
y .
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November 2001 SIGCOMM Internet Measurement Workshop
Frame Rate vs. Network Configuration
Modem: 19% (550)DSL/Cable: 30% (874)T1/LAN: 51% (1468)
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November 2001 SIGCOMM Internet Measurement Workshop
Bandwidth vs. Network Configuration
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 100 200 300 400 500
Average Bandwidth (Kbps)
Cum
ulat
ive
Den
sity
56k Modem
DSL/Cable
T1/LAN
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November 2001 SIGCOMM Internet Measurement Workshop
Outline
• Introduction
• RealVideo
• Methodology
• Results
• Analysis– Frame Rate– Jitter – Perceived Quality
• Conclusions
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November 2001 SIGCOMM Internet Measurement Workshop
Jitter
• Frame rate alone not enough– Also need smooth playout– High frame rate but choppy playout can be as
bad as frame loss [CT99]
• Variation in frame playout interval called jitter– Standard deviation
• Buffering can reduce jitter [RKTS94, SJ95]
– But can still have residual jitter
• Quantitative impact of residual jitter on perceived quality scarce– 50 ms imperceptible, 300 ms very rough
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November 2001 SIGCOMM Internet Measurement Workshop
Overall Jitter
0102030405060708090
100
50 550 1050 1550 2050 2550 3050
Jitter (ms)
Cu
mu
lati
ve
De
ns
ity (%
)
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November 2001 SIGCOMM Internet Measurement Workshop
Jitter vs. Network Configuration
0
10
20
30
40
50
60
70
80
90
100
50 550 1050 1550 2050 2550 3050Jitter (ms)
Cu
mu
lati
ve D
en
sit
y (%
)
56K ModemDSL/CableT1/LAN
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November 2001 SIGCOMM Internet Measurement Workshop
Outline
• Introduction
• RealVideo
• Methodology
• Results
• Analysis– Frame Rate – Jitter– Perceived Quality
• Conclusions
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November 2001 SIGCOMM Internet Measurement Workshop
Perceived Quality
• Frame Rate and Jitter not enough– Best frame rate depends upon content [TC01]
• RealServer varies
– Effects of jitter depend upon content [CT99]
• Perceptual Quality– Numeric rating, 0-10
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November 2001 SIGCOMM Internet Measurement Workshop
00.10.20.30.40.50.60.70.80.9
1
0 5 10 15 20 25 30 35
Clips Rated per User
Cu
mu
lati
ve D
en
sit
y
(388 video clips rated)
Clips Rated per User
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November 2001 SIGCOMM Internet Measurement Workshop
Quality vs. Network Configuration
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 1 2 3 4 5 6 7 8 9 10
Quality Rating
Cu
mu
lati
ve D
en
sity
LAN/T1
DSL/Cable
56k Modem
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November 2001 SIGCOMM Internet Measurement Workshop
Conclusions
• Average RealVideo clip has good quality– 10 frames per second
– Nearly imperceptible jitter
• Network configuration– Modems are a bottleneck
– DSL/Cable modems pushing bottleneck towards server
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November 2001 SIGCOMM Internet Measurement Workshop
Future Work
• RealVideo over UDPTCP-Compatible?
• Perceptual quality of streaming video
• Other streaming players and protocols– MediaPlayer, QuickTime
• Effects of caching, CDNs
• Release of customizable RealTracer
• Download IP addresses, Playlist, RealTracer– From Web page
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An Empirical Study of RealVideo Performance Across the Internet
Yubing Wang, Mark Claypool and Zheng Zuo
http://perform.wpi.edu/real-tracer